Coating process.



r 1'. WALTER o. snnnnrne, or PITTSB RGH, rnimsxLvA-nm.

congrats rnoonss.

No Drawing. v H

Toall whomit may concern: v

Be it known that I, WALTER O. SNELLING, a citizen of the United States, anda resident of Pittsburgh, in the county -of Allegheny and. State of:Pennsy1vania, have invented a new and useful Improvement in Coating Processes, of wh ch the following is aspecification.

My invention relates to theproduction of finely-divided material composed of individually coated particles, and it has for its object to provide a simple and effective process of producing finely subdivided material, particularly metallic filings and granules, composed of individual particles coated with varnish or other substances.

in explosives and action of currents of the A special application of my invention is in the production of iron filings, aluminum filings and the like, for use as ingredients in explosives and fireworks.

My process consists essentially in wettinga mass of finely divided material with a suitable liquid coating substance, preferably containing a volatile vehicle or solvent, and exposing the wetted mass to the separating air or other gas, under such conditions that the constituent particles of the mass are kept separate and are dried while thus separated. In this manner,

particles arecoated as individuals, and

not 1n aggregates or lumps.

I have practised the foregoing process in several different ways, one of which consists in placing the wetted mass of material, including a .Volatile liquid, in a closed Vessel or bomb, which is heated to a temperature above the boiling point of the volatile liquid, and then suddenly opened. The sudden expansion of the volatile liquid, and of the gas which it has evolved in the vessel, forcibly drives out the solid particles and thoroughly scatters them, while-at the elevated temperature, the particles are immediately dried and are found to be evenly and individually coated with the varnish or other coating substance.

As indicated above, cation of my process is 'm divided metals, which are now fireworks.

an .important applitreating finely largely used Aluminum filings, for example, manufacture of'explosives, and iron filings are common ingredients in certain forms of sparkling fireworks. It is found 56 sive mixtures containing metallic fragments deteriorate rapidly, for the reason that the I Specification of Letters Patent. Application filed August 2; l915. Serial No. 48,124.

or other ox1dizing agents that mable coating for providing with coatingsof anykind. Ordinary var are employed in the that explo- Patented Nov, 14,1916.

metals are quickly. oxidized by the nitrates these mixtures. I,

According to my'present invention, I-ob- .viate the difficulty just mentioned by protecting the metallic particles with-a coating WhlCh resists slow oxidation, but which is are used in I preferably combustible. .Convenient var- I nishes for this purpose are composedof solid organic esters, nitrocellulose, for example,

dissolved in appropriate solvents, such as alcohol, ether, benzol, acetone, and the like. Celluloid dissolved in a suitable solvent also forms. a deslrable waterproof and inflam- It is not to tion is restricted to the coating of metallic particles with inflammable substances,isince my process may be employed-equally well other kinds of small objects nishes, containing shellac, copal or other gums, may be used with good results.

Inasmuch as my process may be so widely varied without exceeding the limits of my invention, it is to be understood that no restrictions are to be imposed upon my invention unless indicated inthe appended claims. I claim as my invention: I 1. The process of boating finely-divided be understood that my invenmaterial that comprises treating the material with a liquid coating substance containmg a. vaporizable vehicle, placing the treated mater1al in a closed container, heating boiling point of the said vehicle,and suddenly opening the container.

2. The process of coating finely-divided material. that comprises treating metallic particles with a liquid coating substance containing a vaporizable vehicle, placing the treated material in a closed container, heating the contents of the said container above the boiling point of the said vehicle, and suddenly opening the container.

3. The process of treating finely-divided material that.comprises applying to the material a liquid coating substance v containing a vaporizable vehicle and 'a combustible residue," placing the treated material in a closed container, heating the contents of the said container above the boiling point of the said vehicle, and suddenly opening the container. I

4. The process of coating finely-divided the contents of the said container above the material that comprises applying to the material a liquid coating substance containingv a vaporizable vehicle and a combustible cel- .treating such particles with substance containing a vaporizable vehicle.

' lulose ester, placing the treated material in] a" closed container, heating the contents of .the' container above the boiling point of the I v 'said'vehicle, and suddenly opening the conj 't'ainer.

'5; The process of preparing metallic particles' for pyrotechnic use that comprises a liquid coating and a combustible cellulose ester, placing the treated material in :a closed container,

the contents of the-container above heatin the boiling point of the said vehicle, and g suddenlyopening the container. I

i 04,? ail The of preparing oxidizable particles for pyrotechnic use that comprises treating such particles witharliquid' coating substance containing a vaporizable vehicle and a combustible cellulose ester, placing the treated material in a closed container, 

